Mainland Southeast Asia linguistic area

The Mainland Southeast Asia linguistic area is a sprachbund that includes languages from the Sino-Tibetan, Hmong–Mien (or Miao–Yao), Kra–Dai, Austronesian and Austroasiatic families. These languages are spoken across Mainland Southeast Asia, covering a region that extends from Myanmar through Thailand, Cambodia, Laos and Vietnam into China.

Neighbouring languages across these families, though presumed unrelated, often have similar typological features, which are believed to have spread by diffusion. James Matisoff referred to this area as the "Sinosphere", contrasted with the "Indosphere", but viewed it as a zone of mutual influence in the ancient period.